The present invention relates generally to flash lamp systems such as are often used in airfield lighting systems.
In current airport approach systems, xenon flash lamps are used to produce high intensity white flashing light. These lights may be flashed in two modes, the first being in unison on either side of the runway threshold, which are known as Runway Edge Identifier Light (REIL). The second mode is in sequence pulsing towards the runway known as Medium Intensity Approach Lighting Sequenced Flasher (MALSR) or Approach Lighting Sequenced Flashers (ALSF).
Xenon flash lamps produce very brief pulses of high intensity light that are measured in the microsecond range up to a few milliseconds. Xenon flash lamp systems have some drawbacks that LED (Light Emitting Diode) lamps do not have. For example, xenon flash lamps are rated for 1,000 hours, requiring frequent maintenance. Xenon lamps require extremely high voltages (as high as 15 KV), requiring expensive power supplies along with safety issues and reliability problems associated high voltages. For dimming purposes, the light output for xenon flash lamps are adjusted by switching in and out large amounts of capacitance, requiring additional complexity in the control circuit that impacts cost and reliability.
The aforementioned problems can be avoided by using LED systems. LEDs have life expectancies of over 50,000 hours. LEDs can operate on standard low voltages. Moreover, LEDs can be dimmed by controlling the amount of time that the LEDs are on, which can usually be done without complicated circuitry. However, a problem with prior art LED systems is that they do not provide the same intensity as a xenon flash tube.